Obesity is becoming an increasingly important health problem. In 2007-2008, a National Health and Nutrition Examination Survey showed that 68.3% of Americans were overweight and 33.9% of Americans were obese. The World Health Organization reported in 2008 that 1.5 billion adults (age 20+) were overweight and 500 million adults were obese. Obesity is strongly associated with several major health risk factors, such as diabetes, heart disease, high blood pressure, stroke and higher rates of certain cancers. In the United States, the annual medical expense of obesity has been estimated to be $147 billion in 2008 compared to $78.5 billion in 1998.
Obviously, there is a need to provide individuals with additional and improved methods and devices to monitor consumption of foods and beverages in order to help obtain and maintain a healthy weight. Many methods and devices have been developed over the years to monitor consumption. The three most widely used methods are the eating diary, food frequency questionnaire, and 24-hour dietary recall. However, studies have shown that people tend to underreport their consumption when using these methods, typically by 10-40% per day. In addition, these three methods require a sustained conscious effort on the part of the users to continuously self-monitor. Thus, devices and methods for automatically detecting eating activities during natural daily living are desired.
Current research in the dietetics field focuses on two general approaches. The first approach uses a camera. According to this approach, pictures of foods are taken before and after eating, and the amount consumed is estimated by a trained observer who compares the pictures to a database of portion-varying images of the same foods.
The second approach uses wearable sensors. The technology of wearable sensors in general has significantly advanced the assessment of energy expenditure. Example devices include pedometers and more sophisticated accelerometer-based sleep and physical activity monitors. However, the development of a similar tool for monitoring energy intake has proven elusive. Previous research has been limited to testing in the laboratory using cumbersome measurements of sound and muscle activity at the throat and ear, and multiple sensors tracking torso and limb movements. For example, currently, sensors are worn on various parts of the body to track limb motion and measure sound and muscle activity (for example at the throat), in order to determine when the subject is eating. According to one approach, ear and neck mounted sensors are utilized to detect chewing sounds and swallowing motions. Another approach uses a set of sensors including microphones on the laryngopharynx and mastoid bone portions of the throat, an ambient outward-directed microphone, a microphone in the ear, and a strain sensor on the throat.
However, the above disclosed devices and methods have a variety of disadvantages. For example, studies show that when camera based approaches are utilized, the subjects forget to take pictures. Further, these approaches require a large manual effort by both subjects and the trained observers. Further, presently known wearable sensor approaches, which require sensors worn on the throat and ear or full arms and torso, limit the user's freedom of motion and activities, and due to the exposure of the sensors may have limited social acceptance.
Accordingly, improved devices and methods for detecting the occurrence of eating activities are desired in the art. For example, devices and methods that automatically detect eating activity occurrences that allow full freedom of motion and activities and that provide increased social acceptance would be advantageous.